The US Food and Drug Administration (US FDA) has approved ofatumumab (Arzerra Injection, for intravenous infusion; GlaxoSmithKline) in combination with chlorambucil, for the treatment of previously untreated patients with chronic lymphocytic leukemia (CLL), for whom fludarabine-based therapy is considered inappropriate.
The approval was based on the results of a multi-centre, randomised, open-label trial comparing ofatumumab in combination with chlorambucil to single agent chlorambucil. The trial enrolled 447 patients for whom fludarabine-based therapy was considered to be inappropriate by the investigator for reasons that included advanced age or presence of co-morbidities. In the overall trial population the median age was 69 years (range: 35 to 92 years).
Around 72 per cent of patients had two or more co-morbidities and 48 per cent of patients had a creatinine clearance of <70 mL/min. Patients received ofatumumab as an intravenous infusion according to the following schedule: 300 mg administered on cycle 1 day 1, 1000 mg administered on cycle 1 day 8 and 1000 mg administered on day 1 of all subsequent 28 day cycles. In both arms, chlorambucil was given at a dose of 10 mg/m2 orally on days 1 to 7 every 28 days. Prior to each infusion of ofatumumab, patients received pre-medication with acetaminophen, an antihistamine, and a glucocorticoid.
The primary endpoint of the trial was progression free survival (PFS) as assessed by a blinded Independent Review Committee (IRC) using the 2008 International Workshop on Chronic Lymphocytic Leukemia (IWCLL) update of the National Cancer Institute Working Group (NCI-WG) guidelines. Median PFS was 22.4 months (95 per cent CI: 19.0, 25.2 months) for patients receiving Arzerra in combination with chlorambucil compared to 13.1 months (95 per cent CI: 10.6, 13.8 months) for patients receiving single-agent chlorambucil [hazard ratio 0.57 (95 per cent CI: 0.45, 0.72), stratified log-rank p-value <0.001].
The most common adverse reactions (greater than or equal to five per cent) with ofatumumab in combination with chlorambucil (greater than or equal to two per cent more than in the control arm) were infusion reactions, neutropenia, asthenia, headache, leukopenia, herpes simplex, lower respiratory tract infection, arthralgia and upper abdominal pain. Overall, 67 per cent of patients who received ofatumumab experienced one or more symptoms of infusion reaction. Ten percent of patients experienced a grade 3 or greater infusion reaction.
The results of this randomised trial were adequate to fulfill the postmarketing requirement for GlaxoSmithKline to verify the clinical benefit of ofatumumab and, therefore, the approval of ofatumumab was converted from accelerated approval to regular approval.
EP News Bureau – Mumbai
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